FW82371EB Intel, FW82371EB Datasheet - Page 30

• Manufacturer Part Number: FW82371EB
• Manufacturer: Intel

Specifications of FW82371EB

• Lead Free Status / RoHS Status: Not Compliant

Intel
4.
5.
30
®
82371EB (PIIX4E)
IRQ9 Routing
SCI interrupts, SMBus interrupts and PIRQs can be routed to IRQ9. Any time an SCI, SMB or PIRQ is
programmed to use the internal 8259’s IRQ9, the PIIX4 will ignore the ISA IRQ9 and the interrupts will
behave like level triggered interrupts. The table below describes the implications of the different routing
options.
This clarification applies to all steppings of the PIIX4 and will be incorporated into the next revision of
the PIIX4 datasheet.
NOTE:
SERIRQ Sampling Phase
When referring to the state of the SERIRQ signal the verbiage in section 8.7.1 of the datasheet uses the
words active and low interchangeably as well as the words inactive and high. This text has been changed
to only use the words low and high when referring to the state of the SERIRQ signal. The PIIX4’s 8259
logic determines if the corresponding interrupt on the SERIRQ signal is active or inactive.
This clarification applies to all steppings of the PIIX4 and will be incorporated into the next revision of
the PIIX4 datasheet.
8.7.1 Protocol
Serial interrupt information is transferred using three types of frames: a Start Frame, one or more IRQ
Data frames, and one Stop frame. There are also two modes of operation: Quiet Mode and Continuous
Mode.
Quiet (Active) Mode
To indicate an interrupt, the peripheral brings the SERIRQ signal low for one clock, and then tri-states
the signal. This brings all the state machines from IDLE to the ACTIVE states.
PIIX4 then takes control of the SERIRQ signal by driving it low on the next clock, and continues driving
it low for 3–7 clocks more (programmable). Thus, the total number of clocks low will be 4–8. After those
clocks, PIIX4 drives SERIRQ high for one clock and then tri-state the signal.
Interrupt
SCI
0
0
0
0
0
1
1
1
1
0 = IRQ9 not used by that function
1 = IRQ9 used by that function
non-shared = IRQ9 not shared internally between functions
shared = IRQ9 shared internally between functions
Interrupt
SMBus
0
0
0
1
1
0
0
1
1
PIRQ
0
0
1
0
1
0
1
0
1
ISA IRQ9
X
X
X
X
X
X
X
0
1
No Interrupt
ISA IRQ9 used (edge or level)
ISA IRQ lost, level mode only, non-shared
ISA IRQ lost, level mode only, non-shared
ISA IRQ lost, level mode only, shared
ISA IRQ lost, level mode only, non-shared
ISA IRQ lost, level mode only, shared
ISA IRQ lost, level mode only, shared
ISA IRQ lost, level mode only, shared
Result
Specification Update
R